Try to fix Xcode 12 build

When looking at Homebrew packages that no longer build correctly
( Homebrew/homebrew-core#65000 ) I decided
to take a quick look at mogenerator although I didn't know anything
about the package before.

The build failure at first seemed very odd.  The final link was failing
with:

  error: Build input file cannot be found: '[...]/objroot/mogenerator.build/Release/mogenerator.build/DerivedSources/mogenerator-Info.plist' [...]

At first I assumed that the build-mogenerator-Info-plist.sh script
either did not run or failed to produce the expected file.  However,
after adding some more debugging statements that does not seem to
be the case.  The script definiely runs and you can see the output
from PlistBuddy in the build output:

  Unrecognized Type:
  File Doesn't Exist, Will Create: /tmp/mogenerator-20201222-40012-136lzn9/mogenerator-1.32/objroot/mogenerator.build/Release/mogenerator.build/DerivedSources/mogenerator-Info.plist
  Initializing Plist...

(The first message comes from the use of the '-c "Clear"' line since
"Clear" is supposed to take an argument I guess.. however that seems
unrelated to the build failure)

Digging more into the .pbxproj file I noticed that the "outputPaths"
from the build-mogenerator-Info-plist.sh build step seems to be wrong...
perhaps just a typo.  I fixed that and the build worked.  My theory
is that since xcodebuild wasn't seeing the proper dependency graph it
maybe started the link before the plist was finished being written out?

Anyway it looks like the outputPaths were wrong and repairing that
made this package build again for me.  YMMV.

mogenerator.xcodeproj/project.pbxproj

@@ -446,7 +446,7 @@
 				"$(SRCROOT)/templates/machine.swift.motemplate",
 			);
 			outputPaths = (
-				"$(DERIVED_FILE_DIR)/motemplate-Info.plist",
+				"$(DERIVED_FILE_DIR)/mogenerator-Info.plist",
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 			shellPath = /bin/sh;